Preparation of pyrochlores. A1?xHxTaO3·nH2O (A=Na,K) |
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Authors: | Nobuhiro Kumada Nobuo Ozawa Nobukazu Kinomura Fumio Muto |
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Affiliation: | Institute of Inorganic Synthesis, Yamanashi University, Kofu, Yamanashi 400, Japan |
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Abstract: | Pyrochlores of A1?xHxTaO3·nH2O (A=Na,K) were prepared under the hydrothermal conditions. The values of x for these compounds were increased from 0.3 to 0.5 for A=Na and from 0.2 to 0.5 for A=K by treatment with the distilled water. The compounds with x<0.5 were decomposed to a mixture of NaTaO3 and Na2Ta4O11 for A=Na, or to a mixture of KTaO3 and a tetragonal tungsten bronze phase, and those with x=0.5 to a single phase of A2Ta4O11 at elevated temperatures. Below the decomposition temperatures, defect pyrochlores with oxygen vacancies, , were produced. They were hygroscopic, and in the case of A=K and x=0.5 the original phase was recovered by leaving in air for several hours. |
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